We'll have to wait 'til the end of this diet.
I started off in the pin gang. Like I said earlier Phil, it just doesn't make sense that Diana would machine the groove, then drill/mill the hole in the head to put the pin through to retain the rod, then crimp the body onto the head. It would be easier to just make one drill/mill action and go through the body, head and rod and pin the whole lot. I think for ease of manufacture they just put the rod in the head and the body over the head and crimp the lot and the crimping DOES push enough of the head into the groove to hold the rod in ... but until someone pops one in a lathe and turns down the body to reveal the head I'm guessing.
Yes Rob ... the latest pics show the piston rod nose sheared off at the fore end of the splines. I'm not in a rush to blame Diana for that at this stage. I think that that particular piston assembly has been DIY'd by it's owner. The owner may have noticed that rod was wobbly and the splines area may have worked loose at that point. Maybe he managed to pull the rod out ( kept waggling it in a vice etc like pulling tooth ) and managed to work the grooved area free from the compressed parts on the head. At that point he mega glued the front part of the nose into the very front inside end of the recess in the head. He then drilled and pinned the rod in, using the crude hole we can see inside the crimp mark. Has he weakened the rod just in front of the splines whilst he was waggling it to get it out? We have no idea what DIY abuse that piston rod has experienced from it's owner as he has tried to remove and then secure it.